This Is How Your Body Changes When You’re In A Relationship

In the 1950s, a young man named Kyle Ballard worked as a waiter on the liner ship SS Lurline. The ship sailed between Honolulu and California, running vacationers back and forth between Oahu, San Francisco, and Los Angeles. It’s safe to say there were lots of married couples gathering in the ship’s dining room at mealtime.

Ballard and his fellow waiters got to know their passengers—they were assigned to the same tables every night for the entire five-day trip. Ballard still marvels at the details he and the other waiters noticed about these long-married couples.

“All the experienced waiters agreed on the same thing,” the octogenarian tells HealthyWay. “We could take all 20 people for dinner on sailing night when we first met them and jumble up all persons married at least 40 years, and we could match those couples [because] they looked so much alike.”

Even the height was similar, Ballard says, except the husband was typically a bit taller than the wife.

“Both with about the same weight,” Ballard says. “Even eating and dressing alike. We never stopped making that comparison.”

The thing is, the science backs up Ballard’s story of romantic seaborne adventures from long ago. One 1987 study found that after 25 years of marriage, couples did begin to resemble each other—as in, facially. One working theory is that spouses come to mimic each other’s facial expressions and that leads to physical changes in the face’s musculature over time. Twenty-five years later, you’ve got two faces that look more alike than they did on their wedding day.

If you think that’s incredible, or just incredibly romantic, check out these other physical and physiological changes that long-term relationships can create within our bodies.

1. You start to like the same foods and maybe even the same perfume. But it might not mean what you think it means.

There’s no need to argue over the wedding menu. You may hate onions today, but if your spouse is a die-hard onion ring devotee, give it a few years (or maybe a few decades).

A recent study in the journal Appetite makes the astonishing claim that the longer a couple stays together, the more their preferences in taste and smell line up. The researchers asked 100 couples between the ages of 18 and 68 to rate how much they liked the study’s collection of flavors and scents. Some of the couples had only been together for 3 months; others had 45 years under their belts, but most fell between these extremes.

The data revealed that “both taste and smell preferences are more similar the longer couples have been in a relationship,” according to the study’s abstract. However, in a surprise finding, the researchers report that people in happy marriages don’t necessarily love the same odors.

In fact, relationship satisfaction was “negatively related” to similar preferences in scents. So the happier people said they were in their relationships, the less likely they were to like the same smells. To further complicate matters, this finding did not extend to flavor.

So if you and your spouse still disagree about the smell of frying onions, don’t fret. You might be one of the lucky ones.

2. In the early stages, your brain chemistry goes haywire.

There’s a reason all the pop songs are about love or substance abuse. Or both. Apparently, the initial stages of an intense romantic relationship affect our brain chemistry not unlike an illicit pharmaceutical.

That’s according to David Bennett, a certified counselor and co-runner of the men’s support website The Popular Man.

“This is why when you’re in love, you can barely sleep and will stay up late into the night with your partner, even if you have to get up early the next day,” Bennett says. It’s a good thing this particular effect tends to fade with time and familiarity, or else our work lives would be even rougher.

Oddly, though, serotonin levels actually drop during an experience of romantic love, Bennett explains. A 1999 study in the journal Psychological Medicine found that the loss of serotonin makes the young Romeo’s brain more similar to that of someone with obsessive-compulsive disorder, another psychological state associated with low serotonin.

“This explains why when you’re ‘in love,’ you want to spend time with your partner almost obsessively, and you jealously guard your time with them,” Bennett says.

3. That wedding ceremony line about “sickness and health” is onto something.

You might promise to care for each other “in sickness and in health,” but you’d better plan for these conditions happening to both of you at the same time. Long-married couples have health similarities that seem to go way beyond sympathy pangs.

A 2016 study published in the journal The Gerontologist lays out some of these findings, which include health similarities in some surprising areas. For instance, couples who have been married for decades and decades showed similar grip strength. That might not sound like much, but grip strength is actually a reliable predictor of mortality, so it’s a valuable metric.

Other indicators that long-married couples tended to have in common include cholesterol levels and even kidney health. No big deal, you might say. People choose spouses who are similar to themselves, maybe even on a genetic level.

But wait! The researchers controlled for that. They compared these health similarities in couples who had been married for fewer than 20 years, and didn’t find the same convergence. This seems to be something that grows over time—just like a lifelong romantic relationship itself.

4. Physical fitness habits tend to sync.

One possible explanation for the aforementioned health similarities between long-term couples is that your general predictors of health might align. We’re talking about the big two: diet and exercise.

“Couples influence each other,” says Michele Paiva, a licensed psychotherapist who specializes in body image disorders. “One person might be trying to be more healthy and the other is sabotaging them with ice cream.”

“Perhaps they both go to yoga together and are vegan,” she says. That type of relationship would likely lead to better health outcomes over the years.

So if you really want to maximize the “in health” part of your marriage over the “in sickness” agreement, start working out and eating right—and do it together. It’s also important to be present and loving with one another, Paiva says.

“How the couple relates together intimately and how healthy their relationship is plays a part” in overall health over the long term, she says. “If there is a healthy relationship, there is not self-sabotage or sabotaging of the partner; there is mutual health encouragement.”

Now that sounds romantic.

5. You may feel less actual pain when your partner’s in the room.

Pain is subjective; that’s not to say it isn’t real, just that it’s a physiological event that occurs within your body and that complex factors can influence how bad it can get—what the scientists call “modulation of pain.”

A 2013 literature review published in Frontiers of Human Neuroscience looked at six studies in which romantic partners were present while their loved one was experiencing pain.

Taken as a whole, these studies support the claim that the presence of a partner reduces the intensity of experienced pain for the patient. Of course, nothing in medical science is that simple.

In order to modulate pain, the relationship had to meet certain criteria: The partner couldn’t be seen as acting out of character, and the “adult attachment style”—the overall model of how you connect to others—makes a profound difference. Still, the idea of reducing pain just by having your sweetie hold your hand is a comforting one.

Romantic Love and Health in the Long Term

Ballard points out that his experience aboard the SS Lurline was far from scientific research. It was just something he and the guys would laugh about when the shift was over.

“This was not a study,” he says. “This was nature’s real life.”

The funny thing is what the study that backs up Ballard’s experience also found. The more those long-term couples came to resemble each other over the course of 25 years of cohabitation, the more satisfied they said they were with their marriages. Presence, it seems, makes the heart grow fonder.

Opposites may attract, at least in the beginning. But after a lifetime of partnership, it seems that similarity is one key to true marital bliss. If that’s not just as romantic as taking a liner ship to Hawaii with the love of your life, we don’t know what is.